CODEWITHSUNDEEP
c#cssregexcss-selectors
Osama
Osama

Reputation: 476

Normalize Case of CSS selectors using C#

I'm building a CSS Parser in C#, and I need to "normalize" the case of CSS selectors. What I mean by that is I want to make the tag names lowers case, but keep the classes and ids the way they are.

For example, if I had a string such as:

.Header Td.selected

I want to change normalize the case and change it to:

.Header td.selected

I want to preserve the case of the classes and id's, because in CSS they are case-sensitive. And I need to change the case-insensitive parts to lower case, to avoid storing duplicate CSS rules in my parser.

Therefore, I need some code to be able to distinguish the case-insensitive parts and change them to lower case. How do I do that?

Upvotes: 1

Views: 154

Answers (1)

Markus Jarderot
Markus Jarderot

Reputation: 89241

selector = Regex.Replace(
    selector,
    @"(?<![#.:])(-?\b[^\W\d][-\w]*)",
    m => m.Value.ToLower())

It looks for identifiers that are not preceded by #, . or :.

-?\b[^\W\d][-\w]* or -?[^\W\d][-\w]* matches a CSS identifier, restricted to Basic Latin-1 (U+0000-U+007F).

h           [0-9a-f]
nonascii    [\240-\377]
unicode     \\{h}{1,6}(\r\n|[ \t\r\n\f])?
escape      {unicode}|\\[^\r\n\f0-9a-f]
nmstart     [_a-z]|{nonascii}|{escape}
nmchar      [_a-z0-9-]|{nonascii}|{escape}
ident       -?{nmstart}{nmchar}*

If the string is embedded in full css document, you could use

css = Regex.Replace(
    css,
    @"(?<![#.:])(-?\b[^\W\d][-\w]*)(?=(?:\s*(?:[+>,]|[#.:]?-?[^\W\d][-\w]*|\[.*?]))*\s*\{)",
    m => m.Value.ToLower())

It will make sure the word is part of the selector, and not the declarations. For it to match, the selector have to be followed by {.

Upvotes: 1

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